Tracking system for a reproducing apparatus switchable between first and second tracking controls based on discriminating between first MD type 1 and second MD type 2 optical discs

ABSTRACT

The invention provides an apparatus and method which allows playback of both of a first optical disc wherein the opposite side faces of a groove formed thereon are wobbled at a first predetermined frequency and a second optical disc wherein one of the opposite side faces of a groove formed thereon is wobbled at a second frequency shorter than the first predetermined frequency while the other face of the groove is formed as a flat face. In the apparatus and method, it is discriminated whether an object optical disc of playback is the first optical disc or the second optical disc, and various servo systems are switched based on a result of the discrimination.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a reproduction apparatus and a reproductionmethod which can play back both of a first optical disc wherein wobblesof a first predetermined frequency are formed on the opposite side facesof a groove or a land and a second optical disc wherein wobbles of asecond predetermined frequency are formed on one side face of a grooveor a land.

2. Description of the Related Art

Conventionally, a disc called mini disc (Mini Disc: trademark) is knownwherein grooves wobbled at a predetermined frequency are provided inadvance on a magneto-optical disc of a diameter of 64 mm and data arerecorded on the wobbled grooves.

The mini disc mentioned above has address information recorded in apredetermined modulated condition on the grooves. Access control for themini disc or retrieval of a recordable area of the mini disc isperformed based on the address information.

The mini disc described above allows recording of a compressed audiosignal for 74 minutes in the maximum and is considerably superior inconvenience because it is superior in portability and exhibits a highaccess rate. A mini disc for an audio use may be hereinafter referred tosimply as MD-DA (Mini Disc Digital Audio).

However, since the mini disc described above only has a limitedrecording capacity of FE production circuit 140 Megabytes, it is notsufficient to record a video signal thereon.

Further, while a format called MD-DATA1 is known as a format to be usedto record computer data onto the mini disc, it is disadvantageous inthat the rate in rewriting and reproduction operations is low becausethe recording density of it is as low as FE production circuit 140Megabytes and the minimum recording data length is comparatively large.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a reproductionapparatus and a reproduction method by which servo controls suitable fordifferent magneto-optical discs can be performed to allow reproductionof both of a magneto-optical disc having the conventional data formatMD-DA and MD-DATA1 and another magneto-optical disc having the new dataformat MD-DATA2 for higher density recording.

In order to attain the object described above, according to an aspect ofthe present invention, there is provided a reproduction apparatus forselectively playing back a first optical disc wherein two side faces ofeach of grooves or lands formed thereon are wobbled at a first frequencyand information is recorded on the wobbled grooves or lands and a secondoptical disc wherein one of two side faces of each of grooves or landsformed thereon is wobbled at a second frequency while the other sideface of each of the grooves or lands is formed as a flat face andinformation is recorded on the grooves or lands, comprising an opticalhead for irradiating light upon a predetermined one of the grooves orlands and those of the lands or grooves adjacent the predeterminedgroove or land, first detection means for detecting reflected light fromthe predetermined groove or land, second detection means for detectingreflected light from the lands or grooves adjacent the predeterminedgroove or land, first calculation means for calculating a differencebetween the reflected light of the first detection means and thereflected light of the second detection means to produce a firsttracking error signal, second calculation means for calculating adifference between the reflected light from one and the reflected lightfrom the other of the lands or grooves adjacent the predetermined grooveor land detected by the second detection means, discrimination means fordiscriminating whether an optical disc loaded on the reproductionapparatus is the first optical disc or the second optical disc, andtracking controlling means for performing, when the discrimination meansdiscriminates that the loaded optical disc is the first optical disc,tracking control based on the first tracking error signal produced bythe first calculation means, but performing, when the discriminationmeans discriminates that the loaded optical disc is the second opticaldisc, tracking control based on the second tracking error signalproduced by the second calculation means.

According to another aspect of the present invention, there is provideda reproduction apparatus for selectively playing back a first opticaldisc wherein two side faces of each of grooves or lands formed thereonare wobbled at a first frequency and address information is recorded onthe wobbled grooves or lands in advance and a second optical discwherein one of two side faces of each of grooves or lands formed thereonis wobbled at a second frequency while the other side face of each ofthe grooves or lands is formed as a flat face and address information isrecorded on the grooves or lands in advance, comprising an optical headfor irradiating light upon a predetermined one of the grooves or landsand those of the lands or grooves adjacent the predetermined groove orland, detection means divided into at least two regions in a tracingdirection of the optical head for detecting reflected light from thepredetermined groove or land and the adjacent lands or grooves, firstcalculation means for adding detection outputs of the at least tworegions of the detection means, second calculation means for subtractinga first one from a second one of the detection outputs of the at leasttwo regions of the detection means, discrimination means fordiscriminating whether an optical disc loaded on the reproductionapparatus is the first optical disc or the second optical disc,selection means for switchably selecting one of the first calculationmeans and the second calculation means, controlling means forcontrolling the selection means so that, when the discrimination meansdiscriminates that the loaded optical disc is the first optical disc,the first calculation means is selected, but when the discriminationmeans discriminates that the loaded optical disc is the second opticaldisc, the second calculation means is selected, address extraction meansfor extracting address information based on an output of the first orsecond calculation means selected by the selection means.

According to a further aspect of the present invention, there isprovided a reproduction method for selectively playing back a firstoptical disc wherein two side faces of each of grooves or lands formedthereon are wobbled at a first frequency and information is recorded onthe wobbled grooves or lands and a second optical disc wherein one oftwo side faces of each of grooves or lands formed thereon is wobbled ata second frequency while the other side face of each of the grooves orlands is formed as a flat face and information is recorded on thegrooves or lands, comprising the steps of discriminating whether anobject optical disc of playback is the first optical disc or the secondoptical disc, and producing, when it is discriminated by thediscrimination step that the object optical disc is the first opticaldisc, a tracking error signal based on a side beam and performingtracking control based on the produced tracking error signal, butproducing, when it is discriminated by the discrimination step that theobject optical disc is the second optical disc, a tracking error signalbased on a main beam and a side beam and performing tracking errorcontrol based on the produced tracking error signal.

The above and other objects, features and advantages of the presentinvention will become apparent from the following description and theappended claims, taken in conjunction with the accompanying drawings inwhich like parts or elements denoted by like reference symbols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view showing a track structure of a disc whichcan be used in a reproduction apparatus according to the presentinvention;

FIGS. 2A and 2B are a cross sectional view and a plan view,respectively, showing the track structure of FIG. 1 in an enlargedscale;

FIG. 3 is a table illustrating a plurality of medium formats which areused in the reproduction apparatus according to the present invention;

FIGS. 4, 4A and 4B are block diagrams showing an internal structure of avideo camera to which the present invention is applied;

FIGS. 5, 5A and 5B are block diagrams showing a detailed construction ofa medium driving section of the internal structure of the video camerashown in FIG. 4;

FIGS. 6A, 6B and 6C are a side elevational view, a plan view and a rearelevational view, respectively, showing an appearance of the videocamera shown in FIG. 4;

FIG. 7 is a schematic view showing an example of an area for data storedon a disc which can be played back by the video camera shown in FIG. 4;

FIG. 8 is a diagrammatic view showing an example of arrangement of aphotodetector of an optical head of the video camera shown in FIG. 4;

FIG. 9 is a block diagram showing a construction of an optical detectionsignal processing system of the video camera shown in FIG. 4;

FIGS. 10, 10A and 10B are block diagrams showing a construction of atracking servo circuit system of the video camera shown in FIG. 4;

FIG. 11 is a block diagram showing a construction of an ADIP processingcircuit system of the video camera shown in FIG. 4;

FIG. 12 is a block diagram showing a construction of a spindle servocircuit system of the video camera shown in FIG. 4;

FIGS. 13, 13A and 13B are flow charts illustrating a procedure ofprocessing of the optical detection signal processing system shown inFIG. 9; and

FIG. 14 is a block diagram schematically showing another example of anentire structure of the optical detection signal processing circuit ofthe video camera shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following, a preferred embodiment of the present invention isdescribed with reference to the drawings. In the present embodiment, areproduction apparatus according to the present invention is applied asa recording and reproduction apparatus section of a portable videocamera wherein a camera apparatus section and a recording andreproduction apparatus section which can record and reproduce stillpictures or moving pictures and an audio signal are integrated with eachother. Further, the recording and reproduction apparatus sectionincorporated in the video camera has a construction which can record andreproduce data onto and from a mini disc (MINI DISC: trade mark) whichis known as a kind of magneto-optical disc.

The description proceeds in the following order:

1. Disc format

2. Appearance construction of video camera

3. Internal construction of video camera

4. Construction of medium driving section

5. Example of disc structure for use with video camera

6. Construction of optical detection signal processing circuit system

6-1. Construction of photodetector

6-2. General construction of optical detection signal processing circuitsystem

6-3. Construction of tracking servo circuit system

6-4. ADIP processing circuit system

6-5. Spindle servo circuit system

6-6. Processing operation

7. Modifications

1. Disc Format

The recording and reproduction apparatus section incorporated in thevideo camera in the present embodiment performs recording andreproduction of data, for example, in accordance with a format for datacalled MD-DATA which is used to record and reproduce data onto and froma mini disc which is one of magneto-optical discs. As a format forrecording and reproduction onto and from a mini disc, a format calledMD-DATA1 has been developed for a recording medium for computed data andanother format called MD-AUDIO has been developed for a recording mediumfor MD audio data for an audio signal. The MD-DATA1 format is commonwith a disc format on or an addressing method to a magneto-optical discwhich will be hereinafter described in detail. Further, also anotherformat called MD-DATA2 which allows recording of a higher density thanthat by the format MD-DATA1 has been developed. The video camera in thepresent embodiment can record and reproduce in accordance with theMD-DATA2 format which allows higher density recording than the MD-DATA1format and also in accordance with the MD audio format and the MD-DATA1format. First, a disc format which is a medium format of the MD-DATA2format is described.

FIGS. 1, 2A and 2B schematically show an example of a track structure ofa disc of the MD-DATA2 format. Particularly, FIGS. 2A and 2B are asectional view and a plan view, respectively, showing a portionsurrounded by a broken line A of FIG. 1 in an enlarged scale.

As seen from FIGS. 2A and 2B, on a face of the disc shown, two kinds ofgrooves including a wobbled groove WG to which wobbles are provided anda non-wobbled groove NWG to which no wobble is provided are formed inadvance. The wobbled groove WG and the non-wobbled groove NWG extendsuch that they may form double spirals on the disc with lands Ld formedbetween them.

According to the MD-DATA2 format, the lands Ld are utilized as tracks.The wobbled groove WG and the non-wobbled groove NWG are formed in sucha manner as described above, and the two tracks Tr·A and Tr·B are formedas double spirals independent of each other.

The track Tr·A is a track with respect to which the wobbled groove WG ispositioned on the outer circumference side of the disc and thenon-wobbled groove NWG is positioned on the inner circumference side ofthe disc.

In contrast, the track Tr·B is a track with respect to which the wobbledgroove WG is positioned on the inner circumference side of the disc andthe non-wobbled groove NWG is positioned on the outer circumference sideof the disc.

In other words, it is considered that the track Tr·A has wobbles formedonly on a wall face thereof on the outer circumference side of the discand the track Tr·B has wobbles formed only on a wall face thereof on theinner circumference side of the disc.

In this instance, the track pitch is provided by a distance between thecenters of adjacent portions of the track Tr·A and the track Tr·B, andis 0.95 μm as seen from FIG. 2B.

A wobble of the wobbled groove WG are formed based on a signal whosephysical address on the disc is encoded by FM (Frequency Modulation)modulation and bi-phase modulation. Accordingly, upon recording orreproduction, a physical address on the disc can be extracted bydemodulating reproduction information obtained from the wobble providedto the wobbled groove WG.

Further, address information provided by the wobbled groove WG iseffective commonly to the tracks Tr·A and Tr·B. In other words, aportion of the track Tr·A positioned on the inner circumference side anda portion of the track Tr·B positioned on the outer circumference sidewith respect to a portion of the wobbled groove WG have common addressinformation by a wobble provided to the portion of the wobbled grooveWG.

It is to be noted that such an addressing method as described above isalso called Interlace addressing method. Where the interlace addressingmethod is employed, the track pitch can be made small while, forexample, crosstalk between adjacent wobbles is suppressed. The systemwherein wobbles are formed on a groove to record addresses is calledADIP (Address In Pregroove) method. For the carrier frequency for FMmodulation in formation of wobbles, 88.4 kHz is used for the MD-DATA2format, and 22.05 kHz is used for the MD-DATA1 format.

Further, identification of which one of the tracks Tr·A and Tr·B whichcommonly have the same address information in such a manner as describedabove is being traced is performed in the following manner.

For example, where a three-beam method is employed, it is a possibleidea to cause, when a main beam is tracing a land Ld serving as a track,the remaining two side beams to trace groove portions positioned on theopposite sides of the track being traced.

FIG. 2B illustrates a condition wherein, as a detailed example, a mainbeam spot SPm is tracing the track Tr·A. In this instance, of two sidebeam spots SPs1 and SPs2, the side beam spot SPs1 on the innercircumference side traces the non-wobbled groove NWG while the side beamspot SPs2 on the outer circumference side traces the wobbled groove WG.

In contrast, though not shown, if the main beam spot SPm is tracing thetrack Tr·B, then the side beam spot SPs1 traces the wobbled groove WGwhile the side beam spot SPs2 traces the non-wobbled groove NWG.

In this manner, depending upon whether the main beam spot SPm traces thetrack Tr·A or the track Tr·B, the grooves to be traced by the side beamspots SPs1 and SPs2 are inevitably exchanged between the wobbled grooveWG and the non-wobbled groove NWG.

Detection signals obtained by a photo-detector from reflected light fromthe side beam spots SPs1 and SPs2 exhibit different waveforms dependingupon which one of the wobbled groove WG and the non-wobbled groove NWGis being traced. Accordingly, for example, by discriminating which oneof the side beam spots SPs1 and SPs2 is tracing the wobbled groove WG orthe non-wobbled groove NWG, it can be identified which one of the tracksTr·A and Tr·B is being traced by the main beam.

FIG. 3 illustrates principal specifications of the MD-DATA2 formathaving such a track structure as described above in comparison withthose of the MD-DATA1 format.

First, according to the MD-DATA1 format, the track pitch is 1.6 μm, andthe bit length is 0.59 μm/bit. Further, the laser wavelength λ is λ=780nm, and the numerical aperture NA of the optical head is NA=0.45.

For the recording method, the groove recording method is employed. Inshort, grooves are used as tracks for recording and reproduction.

For the addressing method, a method which makes use of a wobbled grooveformed by forming wobbles as address information on the opposite sidesof a groove formed as a single spiral groove is employed.

For the modulation method for recording data, the EFM (eight to fourteenmodulation) method is employed. Further, for the error correctionmethod, the ACIRC (Advanced Cross Interleave Reed-Solomon Code) isadopted, and convolution type data interleaving is employed for the datainterleave. Consequently, the redundancy of data is 46.3%.

Further, in the MD-DATA1 format, the CLV (Constant Linear Velocity) isadopted for the disc driving method, and the linear velocity of the CLVis 1.2 m/s.

Furthermore, the standard data rate upon recording or reproduction is133 kB/s, and the recording capacity is 140 MB.

In contrast, according to the MD-DATA2 format which can be used by thevideo camera in the present embodiment, the track pitch is 0.95 μm, andthe bit length is 0.39 μm/bit. Thus, it can be seen that both of thetrack pitch and the bit length are shorter than those of the MD-DATA1format. Further, in order to realize, for example, the bit length givenabove, the laser wavelength λ is λ=650 nm, and the numerical aperture NAof the optical head is NA=0.52. Thus, the beam spot diameter at thefocused position is reduced and the band of the optical system iswidened.

For the recording method, the land recording method is employed asdescribed hereinabove with reference to FIGS. 1 and 2, and for theaddressing method, the interlace addressing method is employed. Further,for the modulation method of recording data, the RLL (1, 7) method (RLL:Run Length Limited) which is suitable for high density recording isemployed, and for the error correction method, the RS-PC (Reed-SolomonProduct Code) method is adopted and block closing type data interleavingis employed for the data interleave. As a result of the employment ofthe methods described above, the redundancy of data can be suppressed to19.7%.

Also in the MD-DATA2 format, the CLV is adopted for the disc drivingmethod, and the linear velocity of the CLV is 2.0 m/s. The standard datarate upon recording or reproduction is 589 kB/s. Consequently, arecording capacity of 650 MB can be achieved. According, when comparedwith the MD-DATA1 format, recording of a higher density by more thanfour times is realized.

For example, if recording of moving pictures is performed in accordancewith the MD-DATA2 format, where compression coding according to theMPEG2 (Moving Picture image coding Experts Group 2) is performed formoving picture data, moving pictures for a period of time of 15 to 17minutes can be recorded although it depends upon the bit rate of codeddata. Further, if only audio signal data are to be recorded, wherecompression coding according to the ATRAC2 (Adaptive Transform AcousticCoding 2) is performed for the audio data, recording for a time ofapproximately 10 hours can be performed.

2. Appearance Construction of Video Camera

FIGS. 6A, 6B and 6C are a side elevational view, a plan view and a rearelevational view, respectively, showing an example of an appearance ofthe video camera in the present embodiment.

Referring to FIGS. 6A, 6B and 6C, a camera lens 201 including an imaginglens and a diaphragm to be used for imaging is provided in an exposedcondition on a body 200 of the video camera in the present embodiment.Further, a pair of microphones 202 for collecting sound in stereo fromthe outside upon imaging are provided at top portions of the body 200 asseen in FIG. 6B. In other words, the video camera can perform recordingof an image imaged by the camera lens 201 and recording of a stereoaudio signal collected by the microphones 202.

Further, a display section 6A, a speaker 205 and an indicator 206 areprovided on a side face of the body 200. The display section 6A displaysan imaged image, an image reproduced by the internal recording andreproduction apparatus and so forth thereon. It is to be noted that, asa display device adopted for the display section 6A, for example, aliquid crystal display unit or the like is used though not specificallylimited to this. Further, the display section 6A displays a messagecomposed of letters or characters for informing a user of requiredinformation in response to an operation of the apparatus.

The speaker 205 outputs, upon reproduction of a recorded audio signal,the thus reproduced audio signal. Further, the speaker 205 outputsrequired message sound of, for example, beep sound or the like.

The indicator 206, for example, emits light during a recording operationto inform a user that the video camera is performing a recordingoperation.

A viewfinder 204 is provided on a rear face of the body 200 as shown inFIG. 6C and displays an image fetched from the camera lens 201, acharacter image or the like during a recording operation or in a standbymode. A user can perform imaging while observing the viewfinder 204.

Further, a disc slot 203, a video output terminal T1, a headphone andline terminal T2, and an I/F (interface) terminal T3 are provided on therear face of the body 200. The disc slot 203 is a slot through which adisc serving as a recording medium which can be used with the videocamera in the present embodiment is loaded into or unloaded from thebody 200. The video output terminal T1 is a terminal from which areproduced image signal, a character image signal or the like to anexternal video apparatus, and the headphone and line terminal T2 is aterminal from which a reproduced audio signal is outputted to anexternal audio apparatus or a headphone. The I/F terminal T3 is aninterface input/output terminal through which data is communicated with,for example, an external data apparatus.

Further, various operation members 300, 301 and 304 to 309 to bemanually operated by a user are provided at different locations of thebody 200.

The main dial 300 is an operation switch for setting power supplyon/off, a recording operation or a reproduction operation of the videocamera. When the main dial 300 is at the “OFF” position as seen in FIG.6C, the power supply to the video camera is off, and when the main dial300 is turned to the “STBY” position, the power supply is made availableand the video camera enters a standby condition for a recordingoperation. On the other hand, if the main dial 300 is turned to the “PB”position, then the power supply is made available and the video cameraenters a standby condition for a reproduction operation.

The release key 301 functions as an operation key for starting ofrecording or for a recording shutter when the video camera is in arecording standby condition.

It is to be noted that, in a modification which will be hereinafterdescribed, when the release key 301 is depressed, a pressure level whichis a strength with which the release key 301 is depressed is detected,and the data rate of compressed image data to be recorded onto a disc isvaried in response to the pressure level.

The zoom key 304 is an operation key for operating a zoom conditionbetween a telescopic condition and a wide condition upon imaging.

The eject key 305 is an operation key for unloading a disc loaded in thedisc slot 203.

The reproduction and pause key 306, stop key 307, forward search key 308and reverse search key 309 are prepared for various operations uponreproduction from a disc.

It is to be noted that the appearance of the video camera shown in FIGS.6A, 6B and 6C is a mere example at all and may be modified or variedsuitably in accordance with conditions of use required for the videocamera to which the present invention is applied. Naturally, the kindsand operation manners of the operation keys and the connection terminalsto external apparatus may have various forms.

3. Internal Construction of Video Camera

FIG. 4 is a block diagram showing an example of an internal constructionof the video camera in the present embodiment.

Referring to FIG. 4, a lens block 1 shown actually includes, forexample, an optical system 11 composed of an imaging lens, a diaphragmand other necessary elements. The camera lens 201 described hereinabovewith reference to FIGS. 6A to 6C is included in the optical system 11.Further, the lens block 1 includes a motor section 12 which in turnincludes a focusing motor for performing an automatic focusing operationof the optical system 11 and a zooming motor for moving a zoom lens inresponse to an operation of the zoom key 304.

A camera block 2 principally includes a circuit section for convertingimage light imaged by the lens block 1 into a digital image signal.

A light image of an imaging object which passes through the opticalsystem 11 is provided to a CCD (Charge Coupled Device) 21 of the camerablock 2. The CCD 21 performs photoelectric conversion of the light imageto produce an imaged signal and supplies the imaged signal to a samplehold and AGC (Automatic Gain Control) circuit 22. The sample hold andAGC circuit 22 performs gain adjustment and sample holding processingfor the imaged signal outputted from the CCD 21 to waveform shape theimaged signal. An output of the sample hold and AGC circuit 22 issupplied to a video A/D converter 23, by which it is converted intodigital image signal data.

Signal processing timings of the CCD 21, sample hold and AGC circuit 22and video A/D converter 23 are controlled with timing signals producedby a timing generator 24. The timing generator 24 receives a clock whichis utilized for signal processing by a data processing and systemcontrol circuit 31 in a video signal processing circuit 3 and producesrequired timing signals based on the clock so that signal processingtimings of the camera block 2 are synchronized with processing timingsof the video signal processing circuit 3.

A camera controller 25 executes required control so that theabove-described functioning circuit sections provided in the camerablock 2 may operate appropriately, and executes control for automaticfocusing, automatic exposure adjustment, diaphragm adjustment, zoomingand so forth for the lens block 1.

For example, in automatic focusing control, the camera controller 25controls the angle of rotation of the focusing motor based on focusingcontrol information obtained in accordance with a predeterminedautomatic focusing control method. Accordingly, the imaging lens isdriven into a just focused condition.

Upon recording, the video signal processing circuit 3 performscompression processing for a digital image signal supplied thereto fromthe camera block 2 and a digital audio signal obtained by collection ofsound by means of the microphones 202 and supplies resulting compresseddata as user recording data to a medium driving section 4. Further, thevideo signal processing circuit 3 supplies an image produced from thedigital image signal supplied from the camera block 2 and a characterimage to a viewfinder driving section 207 so that it may be displayed inthe viewfinder 204.

On the other hand, upon reproduction, the video signal processingcircuit 3 performs demodulation processing for user reproduction dataread out from a disc 51 and supplied from the medium driving section 4,that is, compressed image signal data and audio signal data, and outputsdemodulated image and audio signal data as a reproduction image signaland a reproduction audio signal, respectively.

It is to be noted that, in the present embodiment, as a compression anddecompression processing method for image signal data, the MPEG2 (MovingPicture Experts Group 2) is used for moving pictures, and the JPEG(Joint Photographic Coding Experts Group) is used for still pictures.Meanwhile, as a compression and decompression processing method foraudio signal data, the ATRAC2 (Adaptive Transform Acoustic Coding 2) isused.

The data processing and system control circuit 31 of the video signalprocessing circuit 3 principally executes control processing regardingcompression and decompression processing of image signal data and audiosignal data of the video signal processing circuit 3 and processing forcontrolling inputting/outputting of data through the video signalprocessing circuit 3.

Further, controlling processing of the entire video signal processingcircuit 3 including the data processing and system control circuit 31 isexecuted by a video controller 38. The video controller 38 includes, forexample, a microcomputer and so forth and can communicate with thecamera controller 25 of the camera block 2 and a driver controller 46 ofthe medium driving section 4, which will be hereinafter described, forexample, over a bus line or the like not shown.

As basic operations of the video signal processing circuit 3 uponrecording, image signal data supplied from the video A/D converter 23 ofthe camera block 2 is inputted to the data processing and system controlcircuit 31. The data processing and system control circuit 31 suppliesthe inputted image signal data, for example, to a motion detectioncircuit 35. The motion detection circuit 35 performs image processingsuch as motion compensation for the inputted image signal data using,for example, a memory 36 as a working area, and supplies resulting imagesignal data to an MPEG2 video signal processing circuit 33.

The MPEG2 video signal processing circuit 33 uses, for example, a memory34 as a working area to perform compression processing of the inputtedimage signal data in accordance with a format of the MPEG2 and outputs abit stream of the MPEG2 of compressed data as moving pictures. Further,for example, when image data as a still picture is to be extracted fromimage signal data as moving pictures and compression processing is to beperformed for the image data, the MPEG2 video signal processing circuit33 produces compressed image data as a still picture in accordance witha format of the JPEG. It is to be noted that, where compressed imagedata according to a format not of the JPEG but of the MPEG2 is employed,an I picture (Intra-Picture) which is normal image data may possibly behandled as image data of a still picture.

The compressed image signal data compression coded by the MPEG2 videosignal processing circuit 33 is written at a predetermined transfer rateinto and temporarily held by, for example, a buffer memory 32.

It is to be noted that, in a format of the MPEG2, as well known in theart, both of the CBR (Constant Bit Rate) and the VBR (Variable Bit Rate)are supported as a coding bit rate, and the video signal processingcircuit 3 can cope with them.

For example, when image compression processing according to the VBR isto be performed, for example, the motion detection circuit 35 performsmotion detection from image data in units of a micro block within arange of several tens to several hundreds frames in sequence, andtransmits, if some motion is detected, the result of detection as motionvector information to the MPEG2 video signal processing circuit 33.

The MPEG2 video signal processing circuit 33 makes use of requiredinformation including the motion vector information to successivelydetermine quantization coefficients of the individual blocks so that thedata rate of image data after they are compression coded may be acertain required data rate.

An audio signal of sound collected, for example, by the microphones 202is inputted as digital audio signal data to an audio signal compressionencoder and decoder 37 through an A/D converter 64 in a display, imageand audio signal inputting and outputting section 6.

The audio signal compression encoder and decoder 37 performs compressionprocessing for the audio signal data inputted thereto in accordance withthe format of the ATRAC as described above. Also the compressed audiosignal data is written into the buffer memory 32 at a predeterminedtransfer rate by the data processing and system control circuit 31 andtemporarily held by the buffer memory 32.

Compressed image data and compressed audio signal data can be storedinto the buffer memory 32 in such a manner as described above. Thebuffer memory 32 principally has a function of absorbing a difference inrate between the data transfer rate between the camera block 2 or thedisplay, image and audio signal inputting and outputting section 6 andthe buffer memory 32 and the data transfer rate between the buffermemory 32 and the medium driving section 4.

The compressed image data and the compressed audio signal data stored inthe buffer memory 32 are, upon recording, successively read out atpredetermined timings and transmitted to an MD-DATA2 encoder and decoder41 of the medium driving section 4. However, for example, uponreproduction, reading out of data stored in the buffer memory 32 andoperation for recording the read out data onto the disc 51 through themedium driving section 4 and a deck section 5 may be performedintermittently.

Such writing and reading out control of data into and from the buffermemory 32 is executed, for example, by the data processing and systemcontrol circuit 31.

Operation of the video signal processing circuit 3 upon reproduction isgenerally such as follows.

Upon reproduction, compressed image data read out from the disc 51 anddecoded in accordance with the MD-DATA2 format by processing of theMD-DATA2 encoder and decoder 41 in the medium driving section 4 andcompressed audio signal data which is user reproduction data aretransmitted to the data processing and system control circuit 31.

The data processing and system control circuit 31 stores the compressedimage data and compressed audio signal data inputted thereto once, forexample, into the buffer memory 32. Then, the data processing and systemcontrol circuit 31 reads out the compressed image data and thecompressed audio signal data from the buffer memory 32, for example, ata required timing matched in a reproduction time axis and at a requiredtransfer rate, and supplies the compressed image data to the MPEG2 videosignal processing circuit 33 and supplies the compressed audio signaldata to the audio signal compression encoder and decoder 37.

The MPEG2 video signal processing circuit 33 performs decompressionprocessing for the inputted compressed image data and transmitsresulting image data to the data processing and system control circuit31. The data processing and system control circuit 31 supplies thedecompressed image signal data to a video D/A converter 61 in thedisplay, image and audio signal inputting and outputting section 6.

Meanwhile, the audio signal compression encoder and decoder 37 performsdecompression processing for the compressed audio signal data inputtedthereto and supplies the decompressed audio signal data to a D/Aconverter 65 in the display, image and audio signal inputting andoutputting section 6.

In the display, image and audio signal inputting and outputting section6, the image signal data inputted to the video D/A converter 61 isconverted into an analog image signal by the video D/A converter 61 andare inputted to a display controller 62 and a composite signalprocessing circuit 63.

The display controller 62 drives the display section 6A in accordancewith the image signal inputted thereto so that a reproduction image isdisplayed on the display section 6A. Not only an image obtained byreproduction from the disc 51, but also an imaged image obtained byimaging by means of the camera section including the lens block 1 andthe camera block 2 can be displayed substantially on the real time basison the display section 6A.

Further, in addition to such a reproduction image and an imaged image asdescribed above, also a message composed of letters, characters and soforth for informing the user of particular information in response to anoperation of the apparatus is displayed as described hereinabove. Suchmessage display as just described may be realized, for example, byexecuting, under the control of the video controller 38, processing ofcomposing image signal data such as required letters or characters withimage signal data to be outputted from the data processing and systemcontrol circuit 31 to the video D/A converter 61 so that the requiredletters, characters and so forth may be displayed at predeterminedpositions.

The composite signal processing circuit 63 converts the analog imagesignal supplied thereto from the video D/A converter 61 into a compositesignal and outputs the composite signal to the video output terminal T1.If the video camera is connected, for example, to an external monitorunit or the like through the video output terminal T1, then an imagereproduced by the video camera can be displayed on the external monitorunit.

Meanwhile, audio signal data inputted from the audio signal compressionencoder and decoder 37 to the D/A converter 65 in the display, image andaudio signal inputting and outputting section 6 is converted into ananalog audio signal by the D/A converter 65 and outputted to theheadphone and line terminal T2. Further, since the analog audio signaloutputted from the D/A converter 65 is outputted also to a speaker SPthrough an amplifier 66, reproduction sound or the like is outputtedfrom the speaker SP.

The medium driving section 4 principally encodes, upon recording,recording data so that the recording data may be suitable for recordingonto a disc in accordance with the MD-DATA2 format or the MD-DATA1format, and transmits the encoded data to the deck section 5. However,upon reproduction, the medium driving section 4 performs decodingprocessing for data read out from the disc 51 by the deck section 5 toobtain reproduction data and transmits the reproduction data to thevideo signal processing circuit 3.

The MD-DATA2 encoder and decoder 41 of the medium driving section 4receives, upon recording, recording data which include compressed imagedata and compressed audio signal data from the data processing andsystem control circuit 31, performs predetermined encoding processingfor the received recording data in accordance with the MD-DATA2 format,and temporarily stores the encoded data into a buffer memory 42. Then,the MD-DATA2 encoder and decoder 41 reads out the encoded data atrequired timings from the buffer memory 42 and transmits them to thedeck section 5.

Upon reproduction, the MD-DATA2 encoder and decoder 41 performs decodingprocessing in accordance with the MD-DATA2 format or the MD-DATA1 formatfor a digital reproduction signal read out from the disc 51 and inputtedthereto through an A/D converter 43 and an RF (Radio Frequency) signalprocessing circuit 44, and transmits the decoded digital reproductionsignal as reproduction data to the data processing and system controlcircuit 31 of the video signal processing circuit 3.

It is to be noted that, also in this instance, if necessary, thereproduction data are stored once into the buffer memory 42, and dataread out at required timings from the buffer memory 42 are transmittedto the data processing and system control circuit 31. Such writing andreading out control for the buffer memory 42 as described above isexecuted by the driver controller 46.

It is to be noted that, even in such a case wherein, for example, uponplaying back of the disc 51, a servo system or the like is disordered bya disturbance or the like and reading out of a signal from the disc 51is disabled, if a reproduction operation for the disc 51 isre-established within a time corresponding to the read out data storedin the buffer memory 42, then the continuity in time series of thereproduction data can be maintained.

In the present embodiment, an optical detection signal in the form ofcurrent obtained by the photodetector of an optical head 53 of the decksection 5 which receives laser light irradiated upon and reflected fromthe disc 51 is outputted as an analog signal as a result of current tovoltage conversion (hereinafter referred to simply as I-V conversion) bythe optical head 53 side.

In the medium driving section 4 in the present embodiment, the opticaldetection signal in the form of a voltage is converted from an analogsignal into a digital signal by the A/D converter 43. Then, the opticaldetection signal in the form of a digital signal is supplied to the RFsignal processing circuit 44.

The RF signal processing circuit 44 performs required digital signalprocessing for the optical detection signal inputted thereto to produce,for example, an RF signal as reproduction data, and servo controlsignals such as a focusing error signal and a tracking error signal forservoing control to the deck section 5. The RF signal is inputted to anMD-DATA2 encoder and decoder 41.

Meanwhile, the servo control signals produced by the RF signalprocessing circuit 44 are supplied to a servo circuit 45. The servocircuit 45 executes required servoing control of the deck section 5based on the servo control signals inputted thereto.

In the present embodiment, the video camera includes an encoder anddecoder 47 for the MD-DATA1 format so that recording data supplied fromthe video signal processing circuit 3 may be encoded in accordance withthe MD-DATA1 format and recorded onto the disc 51, or, where data readout from the disc 51 are data encoded in accordance with the MD-DATA1format, decoding processing of the data is performed and resulting datacan be outputted to the video signal processing circuit 3. In short, thevideo camera in the present embodiment is constructed so as to becompatible with both of the MD-DATA2 format and the MD-DATA1 format.

The driver controller 46 is a functioning circuit section for generallycontrolling the medium driving section 4.

The deck section 5 is a section which includes mechanisms for drivingthe disc 51. Though not shown in FIG. 4 but shown in FIG. 6C, the decksection 5 can unloadably receive a disc 51 and includes a mechanismwhich allows exchanging of the disc 51 by an operation of a user, thatis, the disc slot 203. Further, the disc 51 here is presupposed to be amagneto-optical disc which matches with the MD-DATA2 format or theMD-DATA1 format.

In the deck section 5, the disc 51 loaded is driven to rotate at a CLVby a spindle motor 52 which is driven to rotate at a CLV. Upon recordingor reproduction, laser light is irradiated upon the disc 51 by theoptical head 53.

The optical head 53 outputs, upon recording, laser light of a high levelnecessary to heat a recording track to its Curie temperature, butoutputs, upon reproduction, laser light of a comparatively low levelsufficient to detect data from reflected light by a magnetic Kerreffect. To this end, the optical head 53 includes a laser diode servingas laser outputting means, an optical system including a polarizing beamsplitter, an objective lens and so forth and a detector for detectingreflected light though not particularly shown in FIG. 4. The objectivelens provided in the optical head 53 is held for movement in a radialdirection of the disc and in a direction toward or away from the disc,for example, by a 2-axis mechanism.

A magnetic head 54 is disposed at a position opposing to the opticalhead 53 across the disc 51. The magnetic head 54 applies a magneticfield modulated in accordance with recording data to the disc 51.

Further, though not shown, the deck section 5 includes a sled mechanismdriven by a sled motor 55. As the sled mechanism is driven, the entireoptical head 53 and the magnetic head 54 can be moved in a radialdirection of the disc.

An operation section 7 corresponds to the operation keys 300 to 310 andso forth shown in FIG. 6C, and operation information of any of theoperation keys by a user is supplied, for example, to the videocontroller 38. The video controller 38 supplies operation informationand control information for causing necessary operations correspondingto an operation by the user to be performed by pertaining sections tothe camera controller 25 and the driver controller 46.

An external interface 8 is provided to allow communication of databetween the video camera and an external apparatus and is provided, forexample, between the I/F (interface) terminal T3 and the video signalprocessing circuit as seen in FIG. 4. It is to be noted that, while theexternal interface 8 is not specifically restricted here, for example,an IEEE 1394 interface or the like may be adopted.

For example, where an external digital image apparatus and the videocamera in the present embodiment are interconnected through the I/Fterminal T3, an image imaged by the video camera or an audio signal canbe recorded into the external digital image apparatus. Further, whereimage or audio signal data or the like reproduced by an external digitalimage apparatus is taken in through the external interface 8, it can berecorded onto the disc 51 in accordance with the MD-DATA2 format or theMD-DATA1 format.

A power supply block 9 makes use of dc power supply obtained from abuilt-in battery or dc power supply produced from commercial ac powersupply to supply required power supply voltages to the functioningcircuit sections. The power supply on and off operation of the powersupply block 9 is controlled by the video controller 38 in response toan operation of the main dial 300 described hereinabove.

Further, during recording operation, the video controller 38 controlsthe indicator 206 to execute its lighting operation.

4. Construction of Medium Driving Section

Subsequently, a detailed construction of functioning circuit sectionsfor the MD-DATA2 format extracted from the construction of the mediumdriving section 4 shown in FIG. 4 is described with reference to a blockdiagram of FIG. 5. It is to be noted that, while the deck section 5 isshown together with the medium driving section 4 in FIG. 5, since theinternal construction of the deck section 5 is described above withreference to FIG. 4, overlapping description of it is omitted here toavoid redundancy.

In the present embodiment, an optical detection signal in the form ofcurrent outputted from the photodetector of the optical head 53 isconverted into another optical detection signal in the form of a voltageby a current to voltage converter provided in the optical head 53 and isoutputted to the medium driving section 4 after its noise resistingproperty is reinforced. It is to be noted that the construction of theoptical detection signal outputting circuit which includes thephotodetector and the current to voltage converter of the optical head53 is hereinafter described.

The optical detection signal in the form of a voltage of an analogsignal inputted to the medium driving section 4 is converted into adigital signal by the A/D converter 43. A digital output of the A/Dconverter 43 is supplied to an RF amplifier 101 and a matrix amplifier107 in the RF signal processing circuit 44.

The RF amplifier 101 performs digital signal processing to produce areproduction RF signal (binary digitized RF signal) in the form of adigital signal from the optical detection signal inputted thereto.

The binary digitized RF signal is supplied to the MD-DATA2 encoder anddecoder 41, in which gain adjustment, clamping processing and so forthare performed by an AGC and clamping circuit 103, and a resulting signalis inputted to an equalizer and PLL (Phase Locked Loot) circuit 104.

The equalizer and PLL circuit 104 performs equalization processing forthe binary digitized RF signal inputted thereto and outputs a resultingsignal to a Viterbi decoder 105. Further, the binary digitized RF signalafter the equalization processing is inputted to a PLL circuit, by whicha clock CLK synchronized with the binary digitized RF signal (RLL (RunLength Limited) (1, 7) code train) is extracted.

The frequency of the clock CLK corresponds to the speed of rotation ofthe disc at present. Therefore, a CLV processor 111 receives the clockCLK from the equalizer and PLL circuit 104, compares the clock CLK witha reference value which corresponds to a predetermined CLV velocityillustrated in FIG. 3 to obtain error information, and utilizes theerror information as a signal component for production of a spindleerror signal SPE. Further, the clock CLK is used as a clock for requiredprocessing of the signal processing circuit systems beginning with, forexample, an RLL (1, 7) demodulation circuit 106.

The Viterbi decoder 105 performs decoding processing in accordance witha Viterbi decoding method for the binary digitized RF signal inputtedthereto from the equalizer and PLL circuit 104. Consequently,reproduction data in the form of an RLL (1, 7) code train are obtained.

The reproduction data are inputted to the RLL (1, 7) demodulationcircuit 106, by which a data stream for which RLL (1, 7) demodulationhas been performed is obtained.

The data stream obtained by the demodulation processing of the RLL (1,7) demodulation circuit 106 is written into the buffer memory 42 througha data bus 114 so that it is expanded on the buffer memory 42.

The data stream expanded on the buffer memory 42 first undergoes errorcorrection processing in units of an error correction block inaccordance with the RS-PC (Reed-Solomon Product Code) method by an ECC(Error Correction Code) processing circuit 116, and. then undergodescramble processing and EDC decoding processing, that is, errordetection processing, by a descramble and EDC (Error Detect Code)decoding circuit 117.

The data obtained by such processing as described above are reproductiondata DATAP. The reproduction data DATAp are transmitted, for example,from the descramble and EDC decoding circuit 117 to the data processingand system control circuit 31 of the video signal processing circuit 3at a transfer rate in accordance with the transfer clock generated by atransfer clock generation circuit 121.

The transfer clock generation circuit 121 is a section which uses, forexample, quartz to generate a transfer clock of an appropriatefrequency, that is, a data transfer rate, when transfer of data betweenthe medium driving section 4 and the video signal processing circuit 3or transfer of data between different functioning circuit sections inthe medium driving section 4 is to be performed.

Further, the transfer clock generation circuit 121 generates clocks ofrequired frequencies to be supplied to the functioning circuit sectionsof the medium driving section 4 and the video signal processing circuit3 in response to an operation condition of the video camera.

The matrix amplifier 107 performs required calculation processing bydigital signal processing for the optical detection signal inputtedthereto to extract a tracking error signal TE, a focusing error signalFE, groove information GFM (Groove Frequency Modulation) which is aninformation signal including absolute address information recorded asthe wobbled groove WG on the disc 51, and so forth and supplies them tothe servo circuit 45. In particular, the tracking error signal TE andfocusing error signal FE extracted in this manner are supplied to aservo processor 112, and the groove information GFM is supplied to anADIP band-pass filter 108.

It is to be noted that, while, as described hereinabove, the presentembodiment is compatible with both of the MD-DATA1 format and theMD-DATA2 format, in a corresponding relationship to this, requiredsignal processing of the matrix amplifier 107 is controlled by thedriver controller 46 so that the operation of the matrix amplifier 107may be switched depending upon whether the format of a disc which makesan object of recording or reproduction is the MD-DATA1 format or theMD-DATA2 format. This will be hereinafter described.

The groove information GFM band limited in accordance with a frequencyof the wobbles by the ADIP band-pass filter 108 is supplied to an A or Btrack detection circuit 109 and an ADIP decoder 110.

The A or B track detection circuit 109 discriminates, for example, basedon the method described. hereinabove with reference to FIG. 2B from thegroove information GFM inputted thereto whether the track being tracedat present is the track TR·A or the track TR·B, and outputs a result ofthe discrimination as track discrimination information to the drivercontroller 46. Meanwhile, the ADIP decoder 110 performs FM demodulationprocessing and required decoding processing for the groove informationGFM inputted thereto to extract an ADIP signal which is absolute addressinformation on the disc, and outputs the ADIP signal to the drivercontroller 46. The driver controller 46 executes required controllingprocessing based on the track discrimination information and the ADIPsignal.

To the CLV processor 111, the clock CLK from the equalizer and PLLcircuit 104 and the ADIP signal obtained by the ADIP decoder 110 areinputted.

The CLV processor 111 utilizes, for example, signals inputted thereto insuch a manner as described above to produce a spindle error signal SPEfor CLV servo control based on an error signal obtained by integrationof a phase error of the ADIP signal from the clock CLK, and outputs thespindle error signal SPE to the servo processor 112. In this instance,depending upon the construction of the CLV processor 111, also an errorsignal component obtained by comparison between the frequency of theADIP signal and a target value corresponding to a predetermined CLVvelocity is utilized as a component of the spindle error signal SPE. Itis to be noted that required operation to be executed by the CLVprocessor 111 is controlled by the driver controller 46.

The servo processor 112 produces a tracking control signal, a focusingcontrol signal, a sled control signal, a spindle control signal and someother servo control signals based on the tracking error signal TE,focusing error signal FE and spindle error signal SPE inputted theretoin such a manner as described above and a track jumping instruction, anaccessing instruction and so forth from the driver controller 46, andoutputs the thus produced control signals to a servo driver 113.

The servo driver 113 produces required servo drive signals based on theservo control signals supplied thereto from the servo processor 112. Theservo drive signals include two 2-axis drive signals for driving thetwo-axis mechanism for a focusing direction and a tracking direction, asled motor driving signal for driving the sled mechanism, and a spindlemotor driving signal for driving the spindle motor 52.

Since such servo drive signals as described above are inputted to thedeck section 5, focusing control and tracking control for the disc 51and CLV control for the spindle motor 52 are performed.

When a recording operation to the disc 51 is to be performed, forexample, recording data DATAr are inputted from the data processing andsystem control circuit 31 of the video signal processing circuit 3 to ascramble and EDC encoding circuit 115. The recording data DATAr areinputted, for example, in synchronism with a transfer clock of the datatransfer rate generated by the transfer clock generation circuit 121.

The scramble and EDC encoding circuit 115 writes and expands therecording data DATAr, for example, into and on the buffer memory 42 andperforms data scrambling processing and EDC encoding processing, whichis processing of adding an error detection code in accordance with apredetermined method, for the recording data DATAr. After thisprocessing, error correction codes according to the RS-PC system areadded to the recording data DATAr expanded in the buffer memory 42, forexample, by the ECC processing circuit 116.

The recording data DATAr processed in such a manner as described aboveare read out from the buffer memory 42 and supplied to an RLL (1, 7)modulation circuit 118 over the data bus 114.

The RLL (1, 7) modulation circuit 118 performs RLL (1, 7) modulationprocessing for the recording data DATAr inputted thereto and outputsrecording data in the form of an RLL (1, 7) code train obtained in thismanner to a magnetic head driving circuit 119.

By the way, the MD-DATA2 format adopts a laser strobe magnetic fieldmodulation method as a recording method for a disc. The laser strobemagnetic field modulation is a recording method wherein a magnetic fieldmodulated with recording data is applied to a recording face of a discand laser light to be irradiated upon the disc is emitted in pulses insynchronism with the recording data.

According to the laser strobe magnetic field modulation method describedabove, the process of formation of a pit edge recorded on a disc doesnot rely upon a transition characteristic such as a reversing rate ofthe magnetic field, but is determined by an irradiation timing of alaser pulse.

Consequently, with the laser strobe magnetic field modulation method,when compared with, for example, a simple magnetic field modulationmethod wherein laser light is irradiated steadily upon a disc and amagnetic field modulated with recording data is applied to a recordingface of the disc, it is very easy to considerably reduce jitters ofrecording pits. In short, the laser strobe magnetic field modulationmethod is a recording method which is superior in recording of a highdensity to the simple magnetic field modulation method.

The magnetic head driving circuit 119 of the medium driving section 4applies a magnetic field modulated with the recording data inputtedthereto from the magnetic head 54 to the disc 51. Meanwhile, the RLL (1,7) modulation circuit 118 outputs a clock synchronized with therecording data to a laser driver 120. The laser driver 120 drives thelaser diode of the optical head 53 in response to the clock inputtedthereto so that laser pulses synchronized with the recording datagenerated as a magnetic field by the magnetic head 54 may be irradiatedupon the disc. In this instance, the laser pulses emitted and outputtedfrom the laser diode have a required laser power suitable for therecording. Recording operation of the laser strobe magnetic fieldmodulation system can be performed by the medium driving section 4 inthe present embodiment in such a manner as described above.

It is to be noted that, in the construction of the MD-DATA2 block shownin FIG. 5, the A/D converter 43, the functioning circuit sections whichform the RF signal processing circuit 44 and the functioning circuitsections which form the servo circuit 45 except A or B track detectioncircuit 109 are, in the present embodiment, circuit sections which arecommonly used by the MD-DATA1 block for the MD-DATA1 format as can beseen also from the construction shown in FIG. 4.

5. Example of Disc Structure for Use with Present Embodiment

Subsequently, an example of a structure of the disc 51 for use with thepresent embodiment is described.

FIG. 7 illustrates a concept of an example of an area structure of thedisc 51 for use with the present embodiment. It is to be noted that themedium format of the disc 51 shown in FIG. 7 is such as describedhereinabove with reference to FIGS. 1 and 2.

As seen from FIG. 7, a magneto-optical recording area of the disc 51into and from which magneto-optical recording and reproduction can beperformed has a management area provided in a section of a predeterminedsize on the innermost circumference side thereof. In the managementarea, principally required management information called U-TOC (Table OfContents), that is, user TOC, which is required for management ofrecording and reproduction of data onto and from the disc is recorded.

For example, in the case of the present embodiment, managementinformation to be used for recording and reproduction in units of a fileas data to be recorded onto or reproduced from the disc and dataindicating image data positions designated to be displayed as thumbnailimages for individual files are stored as the U-TOC.

It is to be noted that the contents of the U-TOC in the management areaare rewritten at any time in accordance with a result of recording ofdata onto the disc till then or a result of editing processing such asdeletion of a file.

A data area is provided on the outer circumference side to themanagement area. Into the data area, principally image data or audiosignal data collected by a user, data fetched through the externalinterface 8 and so forth are recorded.

In this instance, data are recorded into the data area in such a formthat they are managed in units of a file. Further, recording orreproduction data of each file is managed based on the U-TOC stored inthe management area in such a manner as described above.

The U-TOC recorded in the management area is read out, for example, uponloading of the disc, and is stored into, for example, a predeterminedarea of the buffer memory 42 of the medium driving section 4 or thebuffer memory 32. Then, upon recording of data or upon editing, theU-TOC stored in the buffer memory is rewritten in response to a resultof the recording or a result of the editing. Thereafter, at apredetermined opportunity or timing, the U-TOC of the disc 51 isrewritten or updated based on the contents of the U-TOC stored in thebuffer memory.

It is to be noted that the example of the structure of the disc shown inFIG. 7 is a mere example at all, and the physical positionalrelationship of the areas in a radial direction of the disc may bevaried in accordance with actual conditions of use and so forth.Further, if necessary, a further area into which some otherpredetermined kind of data is to be stored may be provided additionally.

6. Construction of Optical Detection Signal Processing Circuit System

6-1. Construction of Photo-detector

In the following, a construction of the optical detection signalprocessing circuit in the present embodiment is described. The opticaldetection signal processing circuit in the present embodiment includesan optical detection signal outputting circuit which converts receptionlight current obtained by the photo-detector of the optical head 53 ofthe deck section 5 into a voltage signal and outputs the voltage signalas an optical detection signal, and an optical detection signalprocessing circuit system which includes required ones of thefunctioning circuit sections of the medium driving section 4 includingthe A/D converter 43, RF signal processing circuit 44, servo circuit 45and so forth and executes required signal processing for an opticaldetection signal from the optical detection signal outputting circuit.

Thus, a construction of the photo-detector of the optical head 53 whichdetects reflected light of laser light from a disc is described withreference to FIG. 8.

The photo-detector in the present embodiment is required to have aconstruction which matches with both of the MD-DATA1 format and theMD-DATA2 format. To this end, the photo-detector includes tenphoto-detector elements A, B, C, D, E, F, G, H, I and J arranged in sucha manner as seen in FIG. 8.

Upon the photo-detector elements A, B, C and D and the photo-detectorelement I and the photo-detector element J, a main beam obtained bydividing a laser beam by means of, for example, a Wollaston Prism isirradiated while, upon the photo-detector elements E and F and thephoto-detector elements G and H, two split ones of a sub beam obtainedby the division described above are irradiated.

It is to be noted that signal processing based on optical detectionsignals obtained by the photo-detector elements A to J described aboveis hereinafter described together with a construction of the opticaldetection signal processing circuit system.

6-2. General Construction of Optical Detection Signal Processing CircuitSystem

FIG. 9 shows a construction of principal components which form aconstruction of the entire optical detection signal processing circuitsystem in the present embodiment. It is to be noted that, in thisfigure, those functioning circuit sections which correspond to thecircuit blocks in FIGS. 4 and 5 are denoted by like reference symbols.

An optical detection signal outputting circuit 53A is a circuit sectionincluded in the optical head 53 and outputs detection outputs of thephoto-detector elements A to J as optical detection signals each in theform of a voltage signal.

In FIG. 9, photodiodes which form the photo-detector elements A, B, C,D, E, F, G and H are generally indicated as a photodiode PD1 andphotodiodes which form the photo-detectors I and J are generallyindicated as a photodiode PD2 for convenience of illustration.

Reception light current obtained by reception of reflected laser lightfrom the disc 51 by the photodiode PD1 is inputted to an current tovoltage converter (hereinafter referred to simply as I-V converter) OP1.The I-V converter OP1 converts the inputted reception light current intoa voltage signal in accordance with a gain determined by a feedbackregister R1 and outputs the voltage signal to the A/D converter 43.

Similarly, reception light current obtained by the photodiode PD2 isinputted to another I-V converter OP2, by which it is converted into avoltage signal in accordance with a gain determined by a feedbackregister R2, and the voltage signal is outputted to the A/D converter43.

It is to be noted that actually the I-V converter OPI and the I-Vconverter OP2 are provided individually for the photo-detector elementsA, B, C, D, E, F, G and H and the photo-detector elements I and J,respectively.

The power of laser light to be irradiated upon the disc 51 is set suchthat, for example, it has different values for recording andreproduction so that they may conform with various conditions uponrecording and upon reproduction. Upon recording onto a magneto-opticaldisc, in order to raise the temperature of a recording face of the discto its Curie temperature, a higher laser power than that uponreproduction is required. Accordingly, the reception light current levelobtained by a photodiode is different upon recording and uponreproduction.

Consequently, optical detection signals obtained on the photo-detectorelements A, B, C, D, E, F, G and H side to be utilized in order toobtain servo control signals and an ADIP signal which is addressinformation must be adjusted so that the levels of them may be equalupon recording and upon reproduction.

To this end, in the present embodiment, for example, the feedbackregister R1 of the I-V converter OP1 is formed as a variable resistor,and depending upon whether recording should be performed or reproductionshould be performed, the resistance value of the feedback register R1 isvaried to a required value with a control signal S1 from the drivercontroller 46 to switch the gain of the I-V converter OP1. In thisinstance, the resistance value is varied so that the gain upon recordingmay be lower than the gain upon reproduction.

It is to be noted that, since the photo-detector elements I and J areutilized for production of a reproduction RF signal, that is, sinceoperation of them is rendered effective only upon reproduction, the gainof the I-V converter OP2 which corresponds to the photo-detectorelements I and J need not particularly be switched between uponrecording and upon reproduction.

However, if the laser power upon recording and the laser power uponreproduction are different between the MD-DATA1 format and the MD-DATA2format, then it is advisable to construct the optical detection signaloutputting circuit 53A such that the resistance values of the feedbackregister R1 and the feedback register R2 are variably controlled so thatgains of the I-V converter OP1 and the I-V converter OP2 correspondingto the laser powers may be obtained.

Optical detection signals of the photo-detector elements A to Joutputted from the optical detection signal outputting circuit 53Ahaving such a construction as described above are outputted to the A/Dconverter 43.

In a stage before the optical detection signals are inputted to the A/Dconverter 43, they are each in the form of an analog voltage signal. TheA/D converter 43 converts the optical detection signals into digitalsignals and supplies the digital signals to the RF amplifier 101, afocusing error signal FE production circuit 140, a tracking error signalTE production circuit 141 and a groove information production circuit142 which extracts groove information GFM in accordance with the ADIPmethod.

The FE production circuit 140, TE production circuit 141 and grooveinformation production circuit 142 are functioning circuit sectionswhich form the matrix amplifier 107 shown in FIG. 5. Further, the matrixamplifier 107 and the RF amplifier 101 are functioning circuit sectionsincluded in the RF signal processing circuit shown in FIG. 4.

The FE production circuit 140 makes use of the optical detection signalsfrom the photo-detector elements A, B, C and D to perform calculationprocessing given by

(A+B)−(B+D)

to produce a focusing error signal FE and supplies the focusing errorsignal FE to the servo processor 112.

A detection method for a tracking error signal is different between theMD-DATA1 format and the MD-DATA2 format, which will be hereinafterdescribed in detail. Consequently, the tracking error signal TEproduction circuit 141 in the present embodiment performs switching ofcalculation processing for the optical detection signals depending uponwhether the applicable format is the MD-DATA1 format or the MD-DATA2format to produce a tracking error signal. The switching of thecalculation processing is controlled with a control signal S3 outputtedfrom the driver controller 46.

The tracking error signal TE outputted from the TE production circuit141 is supplied to the servo processor 112.

Further, as described hereinabove with reference to FIG. 3, differentaddressing methods are used for the MD-DATA1 format and the MD-DATA2format. The MD-DATA1 format employs the single spiral double-sidedwobble method while the MD-DATA2 format employs the interlace addressingmethod.

Therefore, the groove information production circuit 142 performsswitching of the calculation processing for the individual opticaldetection signals depending upon whether the disc 51 has the MD-DATA1format or the MD-DATA2 format so that groove information GFM matchingwith each format may be extracted appropriately.

The groove information GFM obtained by the groove information productioncircuit 142 is supplied through the ADIP band-pass filter 108 to theADIP decoder 110, by which an ADIP signal, that is, address information,is obtained.

Here, the ADIP band-pass filter 108 switches its pass-band with acontrol signal S5 from the driver controller 46 in response to afrequency of wobbles which corresponds to the carrier frequency uponmodulation and is different between the MD-DATA1 format and the MD-DATA2format.

It is to be noted that description of constructions for the switching ofcalculation processing by the groove information production circuit 142and the switching of the pass-band of the ADIP band-pass filter 108 ishereinafter described in detail while it is omitted here.

Further, the RF amplifier 101 executes calculation processing for theoptical detection signals obtained from the photo-detector elements Iand J upon reproduction to obtain a reproduction RF signal. Since the RFamplifier 101 in the present embodiment performs calculation as digitalsignal processing, the reproduction RF signal obtained by the RFamplifier 101 is a digitized, that is, binary digitized, signal, or inother words, a binary digitized reproduction RF signal.

The calculation processing of the RF amplifier 101 is common between theMD-DATA1 format and the MD-DATA2 format.

In particular, where the disc is an optical disc for playback only onwhich data are recorded in the form of pits, the RF amplifier 101performs calculation processing for the optical detection signals of thephoto-detector elements I and J given by

I+J

to obtain a reproduction RF signal.

Further, where the disc is a magneto-optical disc on which data can berewritten, the RF amplifier 101 performs calculation processing for theoptical detection signals of the photo-detector elements I and J givenby

I−J

to obtain a reproduction RF signal.

Further, while detailed description and illustration of an internalconstruction are omitted, the RF amplifier 101 switches an equalizationcharacteristic for the reproduction RF signal such that the appliedfrequency characteristic of the reproduction RF signal may be differentbetween the MD-DATA1 format and the MD-DATA2 format.

Such switching of the calculation processing corresponding to the typeof the disc 51, that is, a pit disc for playback only or amagneto-optical disc and switching of the equalization characteristicdepending upon the MD-DATA1 format or the MD-DATA2 format as describedabove are controlled with a control signal S2 outputted from the drivercontroller 46.

As can be recognized from the foregoing description, in the opticaldetection signal processing circuit system in the present embodiment,the signal processing circuit system in a stage following the opticaldetection signal outputting circuit 53A performs digital signalprocessing. Consequently, the functioning circuit sections surrounded byan alternate long and short dash line in FIG. 9 can be formedcollectively as a single digital signal processing IC (IntegratedCircuit) 1300.

6-3. Construction of Tracking Servo Circuit System

FIG. 10 shows an example of a construction of the tracking servo circuitsystem in the optical detection signal processing circuit system. InFIG. 10, as the tracking servo circuit system, an internal constructionprincipally of the tracking error signal TE production circuit 141 isshown. It is to be noted that overlapping description of those circuitsections which correspond to the functioning circuit sections describedhereinabove with reference to FIGS. 4, 5 and 9 is omitted hereto avoidredundancy.

By the way, for the detection method for a tracking error signal of theMD-DATA formats, a 3-beam method is used for the MD-DATA1 format, and aDPP (Differential Push-Pull) method is used for the MD-DATA2 format.

In the 3-beam method corresponding to the MD-DATA1 format, the opticaldetection signals from the photo-detector elements E, F, G and H areutilized to execute calculation processing given by

(E+F)−(G+H)

to obtain a tracking error signal.

In contrast, according to the DPP method corresponding to the MD-DATA2format, in addition to the optical detection signals of thephoto-detector elements E, F, G and H, the optical detection signals ofthe photo-detector elements A, B, C and D are utilized to performcalculation given by

(A+D)−(B+C)=MPP

 (E−F)−(G−H)=SPP

to obtain a main push-pull signal MPP and a sub push-pull signal SPP,and then calculation processing given by

MPP−SPP

is performed to obtain a tracking error signal.

The TE production circuit 141 is constructed so as to produce a trackingerror signal which matches with any of the 3-beam method and the DPPmethod in such a manner as described below.

The TE production circuit 141 includes, as functioning circuit sectionswhich receive the optical detection signals each in the form of adigital signal outputted from the A/D converter 43, an MPP calculationcircuit 160, an SPP calculation circuit 162 and a TE calculation circuit166.

Of the functioning circuit sections, the circuit system on the MPPcalculation circuit 160 and the SPP calculation circuit 162 sidecorresponds to the DPP method while the circuit system on the TEcalculation circuit 166 side corresponds to the 3-beam method.

The MPP calculation circuit 160 uses the optical detection signals ofthe photo-detector elements A, B, C and D to execute calculationprocessing for obtaining a main push-pull signal MPP, that is,(A+D)−(B+C) and outputs a resulting value to a balance adjustmentcircuit 161. The balance adjustment circuit 161 performs adjustment sothat the terms (A+D) and (B+C) of a result of the calculation mayexhibit an appropriate balance and outputs a resulting value to a DPPcalculation circuit 164.

The SPP calculation circuit 162 uses the optical detection signals ofthe photo-detector elements E, F, G and H to execute calculationprocessing of (E−F)−(G−H) to obtain a sub push-pull signal SPP andoutputs the sub push-pull signal SPP to a gain adjustment circuit 163.The gain adjustment circuit 163 performs adjustment of the gain of thesub push-pull signal SPP and supplies the resulting sub push-pull signalSPP to the DPP calculation circuit 164.

The DPP calculation circuit 164 performs calculation processing ofMPP−SPP between the main push-pull signal MPP and the sub push-pullsignal SPP inputted thereto to produce a focusing error signal FE·DPP inaccordance with the DPP method and supplies the focusing error signal FEDPP to an AGC (Automatic Gain Control) circuit 165. The AGC circuit 165performs gain adjustment of the focusing error signal FE·DPP and outputsa resulting signal to the terminal T1 of a switch 169.

The balance setting of the balance adjustment circuit 161, the gainsetting of the gain adjustment circuit 163 and the gain setting of theAGC circuit 165 are controlled with control signals S11, S12 and S14outputted from the driver controller 46, respectively, so that operationconditions required for the DPP method may individually be satisfied.

It is to be noted that the control signals S11, S12 and S14 and S13, S15and S16 which will be hereinafter described are generally denoted as acontrol signal S3 in FIG. 9.

The TE calculation circuit 166 makes use of the optical detectionsignals of the photo-detector elements E, F, G and H to performcalculation processing of (E+F)−(G+H) to obtain a focusing error signalFE·3BM corresponding to the 3-beam method. The focusing error signalFE·3BM undergoes balance adjustment between the term of (E+F) and theterm of (G+H) in a result of the calculation by a balance adjustmentcircuit 167, undergoes gain adjustment by an AGC circuit 168 and is thensupplied to the terminal T2 of the switch 169.

Here, the setting of the gain of the AGC circuit 168 is controlled witha control signal S13 outputted from the driver controller 46.

In the switch 169, the terminal T3 is alternatively connected to theterminal T1 or the terminal T2, and the switching is controlled with acontrol signal S16 outputted from the driver controller 46. The terminalT3 is connected, for example, to an input of a digital tracking servofilter 150 in the servo processor 112.

In the switch 169, if it is discriminated by the driver controller 46that the disc 51 loaded in the deck section 5 has the MD-DATA2 format,then the terminal T1 and the terminal T3 are connected to each other,but if it is discriminated that the disc 51 has the MD-DATA1 format,then the terminal T2 and the terminal T3 are connected to each other.

Consequently, when it is discriminated that the disc 51 has the MD-DATA2format, a tracking error signal TE DPP detected in accordance with theDPP method is supplied to the digital tracking servo filter 150, butwhen it is discriminated that the disc 51 has the MD-DATA1 format, atracking error signal TE·3BM detected in accordance with the 3-beammethod is supplied to the digital tracking servo filter 150.

In the present embodiment, calculation processing and signal processingcorresponding to the DPP method or the 3-beam method as a detectionmethod for a tracking error signal are performed in response to adifference between the MD-DATA2 format and the MD-DATA1 format of thedisc 51 in such a manner as described above.

Further, the tracking error signal TE·DPP obtained in accordance withthe DPP method and the tracking error TE·3BM obtained in accordance withthe 3-beam method have a difference in signal level from each other.

Consequently, for example, in order to correct the difference to executeappropriate tracking servo control, the driver controller 46 outputs acontrol signal S6 to the digital tracking servo filter 150 to controlthe digital tracking servo filter 150 so that it may set different servogains depending upon whether the tracking error signal TE·DPP isinputted or the tracking error signal TE·3BM is inputted.

It is to be noted that the control signal S6 functions also as a signalfor performing switching control of the servo gain for some other servocontrol as hereinafter described.

The digital tracking servo filter 150 performs required filteringprocessing for the tracking error signal TE·DPP detected in accordancewith the DPP method or the tracking error signal TE·3BM detected inaccordance with the 3-beam method and inputted thereto to produce atracking control signal as a servo control signal and outputs thetracking control signal to the servo driver 113.

Due to the construction described above, in the present embodiment,tracking control can be executed in accordance with a detection methodfor a tracking error signal which is different between the MD-DATA1format and the MD-DATA2 format, that is, in accordance with the 3-beammethod or the DPP method.

6-4. ADIP Processing Circuit System

Subsequently, the ADIP processing circuit system of the opticaldetection signal processing circuit system is described.

A block diagram of FIG. 11 shows an example of a construction of theADIP processing circuit system. Referring to FIG. 11, as the ADIPprocessing circuit system, an internal construction principally of thegroove information production circuit 142 is shown. It is to be notedthat overlapping description of functioning circuit sections in FIG. 11similar to those shown in FIGS. 4, 5 and 9 is omitted here to avoidredundancy.

As described hereinabove, as an addressing method, the single spiraldouble-side wobble method is used for the MD-DATA1 format, and theinterlace address method is used for the MD-DATA2 format. Further, thecarrier frequencies, that is, the groove frequencies, for them uponaddress information encoding are different from each other.

Consequently, switching of calculation processing for production ofgroove information is performed by the groove information productioncircuit 142 depending upon whether the disc 51 has the MD-DATA1 formator the MD-DATA2 format.

Referring to FIG. 11, an optical detection signal in the form of adigital signal outputted from the A/D converter 43 is supplied to an MPPcalculation circuit 170 and an ADIP calculation circuit 171.

The MPP calculation circuit 170 performs calculation processing forproducing groove information in accordance with the MD-DATA1 format. TheMPP calculation circuit 170 executes calculation processing of(A+D)−(B+C) to produce a main push-pull signal MPP, and the mainpush-pull signal MPP is outputted as groove information GFM matchingwith the MD-DATA1 format to the terminal T1 of a switch 172.

It is to be noted that, where the MPP calculation circuit 170 and theMPP calculation circuit 160 described hereinabove with reference to FIG.10 are compared with each other, since they execute similar calculationprocessing except that the MPP calculation circuit 160 is a functioningcircuit section corresponding to the MD-DATA2 format and the MPPcalculation circuit 170 is a functioning circuit corresponding to theMD-DATA1 format, if, for example, balance adjustment, gain adjustmentand so forth in a preceding stage or a following stage are set suitably,the MPP calculation circuits 160 and 170 can be formed commonly so thatthey are constructed collectively as a single functioning circuitsection.

The ADIP calculation circuit 171 performs calculation processing forproducing groove information matching with the MD-DATA2 format. The ADIPcalculation circuit 171 executes calculation processing of (A+B+C+D) toproduce groove information GFM matching with the MD-DATA2 format andoutputs the groove information GFM to the terminal T2 of the switch 172.

In the switch 172, the terminal T1 or the terminal T2 is alternativelyconnected to the terminal T3, and the terminal T3 is connected to aninput of the ADIP band-pass filter 108.

Switching of the terminals of the switch 172 is performed with a controlsignal S4 outputted from the driver controller 46. If it isdiscriminated that the disc 51 loaded in the deck section 5 has theMD-DATA1 format, the switch 172 is controlled so that the terminal T1and the terminal T3 are connected to each other. Consequently, grooveinformation obtained by the MPP calculation circuit 170 is supplied tothe ADIP band-pass filter 108.

On the other hand, if it is discriminated that the disc 51 has theMD-DATA2 format, then the switch 172 is controlled so that the terminalT2 and the terminal T3 are connected to each other. Consequently, grooveinformation obtained by the ADIP calculation circuit 171 is supplied tothe ADIP band-pass filter 108.

While groove information formed as wobbles on a disc is obtained bybi-phase modulating an ADIP signal which is address information and FMmodulating the bi-phase modulated ADIP signal, in the presentembodiment, the carrier frequency upon the FM modulation is 22.05 kHzfor the MD-DATA1 format, but is 88.2 kHz for the MD-DATA2 format.

Accordingly, the ADIP band-pass filter 108 is switched such that, whenthe disc 51 has the MD-DATA1 format, a required band-pass correspondingto the carrier frequency 22.05 kHz is set, but when the disc 51 has theMD-DATA2 format, a pass-band corresponding to the carrier frequency 88.2kHz is set.

Also the switching control of the pass-band is performed by the drivercontroller 46 which discriminates the disc format of the disc 51 andoutputs a control signal S5 based on a result of the discrimination.Such change of the pass-band can be performed simply and readily bydigital processing.

By employing such construction as described above, groove informationcan be detected from optical detection signals to obtain addressinformation in accordance with an addressing method which is differentbetween the MD-DATA1 format and the MD-DATA2 format. Further, while, inthe present embodiment, the disc is driven to rotate in accordance withthe CLV method, the embodiment is advantageous also where the CAV(Constant Angular Velocity) system is adopted alternatively.

Further, if necessary, the gain of the 173 in a stage following the ADIPband-pass filter 108 may be switched with a control signal S9 from thedriver controller 48 depending upon whether it is discriminated that thedisc 51 has the MD-DATA1 format or the MD-DATA2 format.

6-5. Spindle Servo Circuit System

Subsequently, a construction of the spindle servo circuit system for CLVdriving the spindle motor 52 is described with reference to FIG. 12. Itis to be noted that overlapping description also of functioning circuitsections in FIG. 12 similar to those shown in FIGS. 4, 5 and 9 isomitted here to avoid redundancy.

While, in the description above with reference to FIG. 5, it isdescribed that the spindle error signal SPE of the CLV processor 111 isproduced based on the ADIP signal obtained by the ADIP decoder 110, itis otherwise possible to adopt a system wherein the spindle error signalSPE is obtained based on a reproduction RF signal for both of theMD-DATA1 format and the MD-DATA2 format.

Accordingly, the spindle servo circuit system shown in FIG. 12 isconstructed such that, for production processing of the spindle errorsignal SPE, one of a system which is based on an ADIP signal and anothersystem which is based on a reproduction RF signal can be selectivelyused.

Referring to FIG. 12, as a circuit system which produces a spindle errorsignal SPE based on an ADIP signal, a phase and frequency detectioncircuit 180 to which an ADIP signal obtained by the ADIP decoder 110 isinputted is provided.

The phase and frequency detection circuit 180 uses, for example, anerror information signal indicative of a frequency difference obtainedby comparison between an ADIP signal frequency and a target value setcorresponding to a defined CLV velocity matching with a disc format andanother error information signal indicative of a phase differencebetween an ADIP signal and the clock CLK to produce a spindle errorsignal SPE. The spindle error signal SPE obtained by the phase andfrequency detection circuit 180 is supplied to the terminal T1 of aswitch 182.

On the other hand, as a circuit system which produces a spindle errorsignal SPE based on a reproduction RF signal, a phase and frequencydetection circuit 181 which receives a reproduction RF signal obtainedby the RF amplifier 101, that is, a binary digitized reproduction RFsignal is provided.

Also the phase and frequency detection circuit 181 uses, for example, anerror information signal indicative of a frequency difference obtainedby comparison between the frequency of a received reproduction RF signaland a target value set corresponding to a defined CLV velocity matchingwith a disc format and another error information signal indicative of aphase error between an ADIP signal and the clock CLK to produce aspindle error signal SPE.

The spindle error signal SPE obtained by the phase and frequencydetection circuit 181 is supplied to the terminal T2 of the switch 182.

Also the switch 182 is constructed such that the terminal T1 or theterminal T2 is alternatively connected to the terminal T3, and theterminal T3 is connected to an input of a digital spindle servo filter151 in the servo processor 112.

The switching of terminal connection of the switch 182 is controlledwith a control signal S7 outputted from the driver controller 46 so thatone of the spindle error signals SPE of the phase and frequencydetection circuit 180 and the phase and frequency detection circuit 181is supplied to the digital spindle servo filter 151.

Here, while various discrimination factors may be available as adiscrimination factor for the terminal switching control by the drivercontroller 46, it is a possible idea to construct the discriminationelement, for example, such that one of the spindle error signals SPEwith which a more appropriate spindle servo controlling condition isobtained in response to a rotation condition of the spindle motor suchas rotation upon starting of rotation or rotation in a condition whereinthe PLL is locked. Further, depending upon the case, it may be possibleto fixedly set the switched condition of the switch 182 in an initialstage.

In the construction shown in FIG. 12, the CLV processor 111 is formedfrom the phase and frequency detection circuits 180 and 181 and theswitch 182.

As described hereinabove with reference to FIGS. 2A and 2B, the CLVvelocity is different between the MD-DATA1 format and the MD-DATA2format such that, for the MD-DATA1 format, it is prescribed to be 1.2m/s which corresponds to approximately 11 Hz as an innermostcircumference rotational velocity, and for the MD-DATA2 format, it isprescribed to be 2.0 m/s which corresponds to approximately 22 Hz as aninnermost circumference rotational velocity.

Consequently, the target value to be compared with the ADIP signalfrequency or the reproduction RF signal frequency by the phase andfrequency detection circuit 180 or 181 must be switched to a requiredvalue in accordance with a disc format. Thus, the spindle servo circuitsystem should be constructed such that also the switching control of thetarget value is performed with a control signal S8A or S8B outputtedfrom the driver controller 46 as seen from FIG. 12.

Further, since the CLV velocity is different depending upon a discformat, the transmission characteristic of the spindle motor 52 itselffor the MD-DATA2 format provides a difference of approximately −6 dBfrom that for the MD-DATA1 format.

Consequently, where the disc 51 has the MD-DATA2 format, the drivercontroller 46 outputs a control signal S6 to perform control ofswitching the servo gain so that correction by +6 dB may be performed bythe digital spindle servo filter 151.

By the construction described above, spindle servo control whichconforms with any of the MD-DATA1 format and the MD-DATA2 format can beachieved.

6-6. Processing Operation

An example of processing operation when operation control of the drivercontroller 46 for the optical detection signal processing circuit systemdescribed hereinabove with reference to FIGS. 9, 10, 11 and 12 isexecuted actually is illustrated in a flow chart of FIG. 13. It is to benoted that, for example, processing operation upon reproduction isillustrated in FIG. 13.

In the processing illustrated in FIG. 13, first in step S101, it isdiscriminated, as a disc type of the disc 51, which one of the MD-DATA1format and the MD-DATA2 format the disc 51 has. The discriminationprocessing may be performed, for example, based on the shape of anidentification shape which is physically formed in a cartridge of thedisc 51 and indicates a distinction between the MD-DATA1 format and theMD-DATA2 format. In this instance, a detection mechanism which candetect the identification shape is provided in the disc slot 203 of thedeck section 5.

Alternatively, for example, identification information representative ofa disc format in management information read out from the managementinformation area of a disc may possibly be utilized.

If it is discriminated in step S101 that the disc 51 has the MD-DATA2format, then the control advances to step S102, but if it isdiscriminated that the disc 51 has the MD-DATA1 format, the controladvances to step S112.

It is to be noted that, in FIG. 13, the MD-DATA1 format is representedin an abbreviated form as “MD1” and the MD-DATA2 format is representedin an abbreviated form as “MD2” for convenience of illustration.

In step S102, control processing for setting circuit operation of thetracking servo circuit system corresponding to the DPP method isexecuted. More particularly, as described hereinabove with reference toFIG. 10, the driver controller 46 outputs a control signal S16 toperform switching control of the switch 169 so that the tracking errorTE·DPP may be inputted to the servo processor 112.

In next step S103, servo gains for focusing servo control, trackingservo control and sled servo control are set so that they may conformwith the MD-DATA2 format. This is performed, as described hereinabovewith reference to FIGS. 9, 10 and 12, by the driver controller 46 whichoutputs a control signal S6 to the digital servo filter corresponding toeach of the servo controls described above.

Thereafter, in step S104, the focusing servo is rendered on. In short,after focusing pull-in control is performed, the focusing servo loop isclosed to start focusing servo control.

In step S105, balance adjustment is performed by the balance adjustmentcircuit 161 provided in the following stage to the MPP calculationcircuit 160 as described hereinabove, and then in step S106, gainadjustment is performed by the gain adjustment circuit 163 in thefollowing stage to the SPP calculation circuit 162. Further, in stepS107, control for gain setting of the AGC circuit 165 is executed.

In step S108, the tracking servo loop is closed to start tracking servocontrol, and then in step S109, sled servo control is started.

In next step S110, control for switching the servo gain so thatcorrection by +6 dB may be performed is performed by the digital spindleservo filter 151 as described hereinabove with reference to FIG. 12.Then in step S111, control for switching the pass-band characteristic ofthe ADIP band-pass filter 108 so as to correspond to 88.2 kHz for theMD-DATA2 format as described hereinabove with reference to FIG. 11 isexecuted, whereafter the control advances to step S121.

On the other hand, if it is discriminated in step S101 that the disc 51has the MD-DATA1 format, then first in step S112, controlling processingfor setting circuit operation of the tracking servo circuit system sothat it may match with the 3-beam method is executed. More particularly,the driver controller 46 outputs a control signal S16 to performswitching control of the switch 169 so that the tracking error TE·3BMmay be inputted to the servo processor 112 as described hereinabove withreference to FIG. 10.

In next step S113, servo gains for focusing servo control, trackingservo control and sled servo control are set such that they may conformwith the MD-DATA1 format. This is performed by the driver controller 46which outputs a control signal S6 to each of the digital servo filtersas described hereinabove with reference to FIGS. 9, 10 and 12.

Then, focusing servo is rendered on in next step S114, whereaftercontrol advances to step S115.

In step S115, balance adjustment of the balance adjustment circuit 167of the TE calculation circuit is performed as described hereinabove withreference to FIG. 10. In next step S116, control for gain setting of theAGC circuit 168 is executed.

In next step S117, the tracking servo loop is closed to start trackingservo control, and then in step S118, sled servo control is started.

In step S119, control for switching the servo gain of the digitalspindle servo filter 151 so that it may conform with the MD-DATA1 formatis executed. In this instance, a lower required gain is set so that alevel by −6 dB with respect to the servo gain set by the processing instep S110 described hereinabove may be obtained.

In next step S120, control for switching the passband characteristic ofthe ADIP band-pass filter 108 so that it may correspond to 22.05 kHz forthe MD-DATA1 format is executed, whereafter the control advances to stepS121.

In step S121, it is waited that the speed of rotation of the spindlemotor converges into a prescribed speed range in which the speed ofrotation can be locked and then the spindle servo loop is closed tostart the spindle servo control.

Then in step S122, the ADIP signal is read out to acquire addressinformation, and in next step S123, controlling processing for readingout data recorded on the disc 51 is executed.

7. Modifications

The operating detection signal processing circuit system in the presentembodiment may have such a modified construction as shown in FIG. 14where the optical detection signal outputting circuit 53A including anI-V converter is not provided in the optical head 53 side.

Referring to FIG. 14, the modified optical detection signal processingcircuit system includes a photo-detector section 53B which outputsoptical detection signals each in the form of current obtained by thephoto-detector elements A to J. The photo-detector section 53B isprovided in the optical head 53.

Further, a digital signal processing IC 1300 shown includes an A/Dconverter 43 and an optical detection signal processing circuit system1200 in the following stage to the A/D converter 43. Here, the opticaldetection signal processing circuit system 1200 corresponds to a circuitsystem which includes the functioning circuit sections in the digitalsignal processing IC 1300 described hereinabove with reference to FIGS.9, 10, 11 and 12.

In such an instance as described above, a current to voltage conversioncircuit 190 is provided between the photo-detector section 53B and thedigital signal processing IC 1300.

The current to voltage conversion circuit 190 converts optical detectionsignals each in the form of current from the photo-detector elements Ato J into voltage signals and supplies the voltage signals to the A/Dconverter 43.

The current to voltage conversion circuit 190 can be formed with asimple construction including a buffer amplifier merely having a currentto voltage conversion function and so forth.

While, in the embodiment described above, where the disc has theMD-DATA2 format, recording is performed on a land of the disc,alternatively recording may be performed on a groove. Further, while,where the disc has the MD-DATA1 format, recording is performed on agroove, alternatively recording may be performed on a land.

Furthermore, while, in the embodiment described above, the presentinvention is applied to a magneto-optical disc, the present inventionmay be applied otherwise to a CD-R or a DVD-RW of the phase variationtype.

It is to be noted that, while it is described that, in the embodimentdescribed above, the MD-DATA formats are used for a medium format, thepresent invention can naturally be applied to any other medium formatonly if the recording medium is an optical recording medium and opticaldetection signal processing is required for recording and reproductionof the optical recording medium.

Further, while, in the foregoing description a case is described whereina construction for obtaining compatibility between the MD-DATA1 formatand the MD-DATA2 format is obtained, also in this regard, the presentinvention can be constructed so that compatibility may be obtainedbetween some other medium formats.

Further, while the foregoing description of the embodiment of thepresent invention is directed to a video camera, the present inventioncan be applied also to a recording and reproduction apparatus in theform of a unitary apparatus which can perform recording or reproductionin accordance with an optical recording medium.

While a preferred embodiment of the present invention has been describedusing specific terms, such description is for illustrative purposesonly, and it is to be understood that changes and variations may be madewithout departing from the spirit or scope of the following claims.

What is claimed is:
 1. A reproduction apparatus for selectively playingback a first optical disc wherein two side faces of each of grooves orlands formed thereon are wobbled at a first frequency and information isrecorded on the wobbled grooves or lands and a second optical discwherein one of two side faces of each of grooves or lands formed thereonis wobbled at a second frequency while the other side face of each ofthe grooves or lands is formed as a flat face and information isrecorded on the grooves or lands, comprising: an optical head forirradiating light upon a predetermined one of the grooves or lands andthose of the lands or grooves adjacent the predetermined groove or land;first detection means for detecting reflected light from thepredetermined groove or land; second detection means for detectingreflected light from the lands or grooves adjacent the predeterminedgroove or land; first calculation means for calculating a differencebetween the reflected light of said first detection means and thereflected light of said second detection means to produce a firsttracking error signal; second calculation means for calculating adifference between the reflected light from one and the reflected lightfrom the other of the lands or grooves adjacent the predetermined grooveor land detected by said second detection means to produce a secondtracking error signal; discrimination means for discriminating whetheran optical disc loaded on said reproduction apparatus is the firstoptical disc or the second optical disc; and tracking controlling meansfor performing, when said discrimination means discriminates that theloaded optical disc is the first optical disc, tracking control based onthe first tracking error signal produced by said first calculationmeans, but performing, when said discrimination means discriminates thatthe loaded optical disc is the second optical disc, tracking controlbased on the second tracking error signal produced by said secondcalculation means.
 2. A reproduction apparatus according to claim 1,wherein said first detection means includes a four-piece detector.
 3. Areproduction apparatus according to claim 1, wherein said discriminationmeans is configured to discriminate based on a first property of acartridge in which the first optical disc is accommodated and a secondproperty of a cartridge in which the second optical disc isaccommodated.
 4. A reproduction apparatus according to claim 1, furthercomprising controlling means for controlling the gain of the first orsecond tracking error signal.
 5. A reproduction apparatus according toclaim 1, further comprising balancing means for balancing the first orsecond tracking error signal.
 6. A reproduction method for selectivelyplaying back a first optical disc wherein two side faces of each ofgrooves or lands formed thereon are wobbled at a first frequency andinformation is recorded on the wobbled grooves or lands and a secondoptical disc wherein one of two side faces of each of grooves or landsformed thereon is wobbled at a second frequency while the other sideface of each of the grooves or lands is formed as a flat face andinformation is recorded on the grooves or lands, comprising the stepsof: discriminating whether an object optical disc of playback is thefirst optical disc or the second optical disc; and producing, when it isdiscriminated by the discrimination step that the object optical disc isthe first optical disc, a tracking error signal based on a side beam andperforming tracking control based on the produced tracking error signal;but producing, when it is discriminated by the discrimination step thatthe object optical disc is the second optical disc, a tracking errorsignal based on a main beam and a side beam and performing trackingerror control based on the produced tracking error signal.
 7. Areproduction method according to claim 6, further comprising the stepof: extracting, when it is discriminated by the discrimination step thatthe object optical disc is the first optical disc, the first frequencyfrom a reproduction signal and controlling rotation of the optical discbased on the extracted frequency; but extracting, when it isdiscriminated by the discrimination step that the object optical disc isthe second optical disc, the second frequency from the reproductionsignal and controlling rotation of the optical disc based on theextracted frequency.